This project will develop statistical methodology to examine the data collected by NICHD through the projects Small-for-Gestational Age Study I and Study II in Alabama and Scandinavia, and the projects Maternally Linked Longitudinal Studies in Missouri and Utah. A host of statistical procedures will be developed to handle questions concerning various issues in perinatal epidemiology. Methodologically, it is planned to generate new and rigorous statistical methods and algorithms that can generally be applied to studies involving repeatedly measured data. The first phase of the project focuses on the fetal growth applications, maternal risk factors, and pregnancy outcomes.